Subterranean wells are drilled for many purposes, including the recovery of hydrocarbons, carbon dioxide, and removal of contaminants. Additionally, subterranean wells are drilled for the purpose of injecting substances back into subterranean formations, such as hydrocarbons into a salt dome, water into a reservoir, and disposal of hazardous material.
The process of drilling subterranean wells consists of drilling a hole in the earth down to a reservoir or formation in which a substance is intended to be removed from or injected. Hereinafter this disclosure will refer to the process in regards to drilling for recovery of hydrocarbons, although the tool of the present application is adapted for the use in any type of drilling operation.
Typically, in the drilling of wells, the well is drilled in sections. After each section of the well is drilled a casing string is placed within the wellbore. Casing is pipe which is placed in the wellbore to form a conduit from the subterranean reservoir to the surface. Casing also prevents the wellbore from collapsing and provides a barrier to the flow of fluids between formations which the wellbore penetrates. Once a string of casing is run into the hole, it is typically cemented in place. It is very common for a well to include more then one section of casing, each section having a different diameter from other sections of casing.
Casing is commonly run into the hole one joint or stand at a time. Each joint is picked up and then connected to the top most joint of the casing string which is typically supported at the rig floor by a casing spider. Power tongs may then be used to threadedly connected the additional casing joint to the casing string in the hole. Once the joint or stand of casing has been connected to the casing string, a casing elevator which normally grips the outside diameter of the casing is lowered over the added joint or stand and activated so as to grip the casing string. The casing string is then lifted by the external casing elevator thus allowing the spider to release the casing string. Once the spider grip has released the casing string the string may be lowered into the wellbore.
As each additional joint or stand of casing is connected to the casing string, as set out above, it is filled with fluid and for running into the hole. This fluid prevents floatation of the casing string, maintains pressure within the well to prevent formation fluid from coming back up the hole, and prevents the casing from collapsing. The filling of each joint or stand of casing as it is run into the hole is the fill-up process. Lowering the casing into the wellbore is typically facilitated by alternately engaging and disengaging elevator slips and spider slips with the casing string in a step wise fashion, facilitating the connection of an additional stand of casing to the top of the casing string as it is run into the hole. The prior art discloses hose assemblies, housings coupled to the uppermost portion of the casing, and tools suspended from the drill hook for filling the casing.
When casing is run into the hole it is sometimes necessary to circulate fluid. Circulating fluid requires pumping a fluid down the interior of the casing, out the bottom of the casing and back up the hole through the annulus between the casing and wellbore. Fluid is circulated through the well when casing gets stuck in the hole, to clean the hole, to condition the drilling fluid, to test the well and surface equipment, and to cement the casing within the wellbore.
Circulation of the fluid is sometimes necessary when resistance is encountered as the casing is lowered into the wellbore, preventing the running of the casing string into the hole. This resistance to running the casing into the hole may be due to such factors as drill cuttings, mud cake, caving of the wellbore, or a tight hole among other factors. In order to circulate the drilling fluid, the top portion of the casing must be sealed so that the interior of the casing may be pressurized with fluid. Since the casing is under pressure the integrity of the seal is critical to safe operation, and to minimize the loss of expensive drilling fluid. Once the obstruction is removed the casing may be run into the hole as before.
Often when casing is stuck in the hole, circulation of fluid alone is insufficient to free the casing. At these times it is necessary to rotate and reciprocate the casing to free it. Heretofore, it was necessary to rig down prior art fill-up and circulating tools to rig up tools to rotate and reciprocate the casing string. In these situations it was impractical to then be able to circulate fluid while the casing is being rotated and reciprocated. This process of rigging up and down is very time consuming, costly, and increases the risk of injury to rig personnel.
Once the casing string is run into the hole to a desired depth it is cemented within the hole. The purpose of cementing the casing is to seal the casing to the wellbore formation. In order to cement the casing within the wellbore it is common practice to remove the assembly which is used to fill and/or to circulate fluid from the drilling rig and a cementing head apparatus is installed atop the casing string. This process is time consuming, requires significant manpower, and subjects the rig crew to potential injury when handling and installing the additional equipment.
The prior art discloses separate devices and assemblies for (1) filling drilling fluid in and circulating fluid through tubular members or strings; (2) lowering, and torquing individual joints or strings of tubulars; (3) rotating and reciprocating tubulars members or strings; and (4) cementing operations. These prior art assemblies requiring re-rigging of equipment each time a new sequence in the running and setting of casing is changed. An internal elevator is disclosed in U.S. Pat. No. 4,320,915 assigned to Varco International, Inc. As disclosed, this prior art internal elevator does not disclose or provide a conduit through the elevator for filling the tubular member with a fluid or circulating fluids through the tubular string.
It would be a benefit therefore, to have an internal elevator adapted for internally gripping tubulars and allowing fluid to be pumped through the tool which may be used with top drive or rotary drilling rigs. It would be a further benefit to have an internal elevator which allows an operator to torque individual tubular joints or strings together or apart, rotate, and reciprocate tubular joints or strings. It would be a still further benefit to have an internal elevator which may used both in filling tubulars with fluid and circulating fluid therethrough. It would be an additional benefit to have an internal elevator which may be used in conjunction with conventional fill-up and circulating tools, and cementing apparatus.